DCV_4_3_B— Directional Control Valve with first-order spool dynamics, a spool with 4 ports, and 3 stable positions; when in the middle position, ports A, B and T are connected, and port P is closed

The DCV_4_3_B component describes a directional control valve with first-order spool dynamics, a spool with 4 ports, and 3 stable positions. When it is in the middle position, ports A, B and T are connected and port P is closed.

The laminar/turbulent flow through the valve is modeled as flow through orifices without cavitation. The commanded opening of the valve is input at commandA or commandB, respectively.

The parameter qnom gives the nominal flow rate of the fully opened flow path at the pressure drop &Delta;pnom.

When the pump pressure and the flow rate are high, the unbalanced forces and flow forces acting on the spool are higher than the force generated by the solenoid and the valve is partially closed. The effect can be modeled by the parameters P_max and coeff_P. Specify the maximum hydraulic power in W (where the valve is still completely open) and use coeff_P to adjust the model to the manufacturer's data. When the specified hydraulic power is exceeded, a warning is printed in the log window (Mode Simulation / Simulation / Show Log).

The movement of the spool is described by a first-order system. This is appropriate for valves that are directly actuated by a spool. The times to shift from the neutral position to an end position (τopening) may be different than the time to shift to the neutral position (τclosing).

Use the modifier(s)

VolumeA(port_A(p(start=1e5,fixed=true)))

and/or

VolumeB(port_A(p(start=1e5,fixed=true)))

and/or

VolumeP(port_A(p(start=1e5,fixed=true)))

and/or

VolumeT(port_A(p(start=1e5,fixed=true)))

to set the initial condition(s) for the pressure of the lumped volume(s) Pa.

Events

There is a new boolean reduceEvents (selected by default) in the Parameters→Advanced section under the Properties tab (). Selecting reduceEvents lets the model use noEvents(expr) to generate fewer events for boolean expressions that should not generate events. In some cases the solver might reduce the stepsize too much and generate a lot of steps. If this happens, try clearing reduceEvents.

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